Unless I'm reading the FR graphs wrongly, I thought the DTECs handle that range particularly well? At least, a WBFK + DTEC should provide sufficient upper mid range response, coupled with my acoustic tuning by increasing inner diameter of passages to ~1.4mm. I can increase this further to boost the 1-2kHz response if I feel that the mids are too recessed.
DTEC with tubing length around 16mm will move peaks to 1,5kHz and further to the left. and you won't be able to level it down much by tubing diameter. As I understand you'll be using 2200 damper which will affect range between 800Hz and 6kHz decreasing response by around 4-6dB.
WBFK, I don't know where you plan to cut it, but it has very flat response and peak around 5-8kHz (depending on tubing).
What I'm saying your frequency response will look like this - bump in bass and mid bass. practically flat (~2-3dB differences) between 700-4kHz and peak at 8-10kHz and then practically flat to 20kHz
It will sound mid-recessed, vocals may sound hollow. Bass and highs will be dominant though.
It also comes down to how good you'll be able to handle phase canceling. You may end up with big gap or peak in certain frequencies.
Edited by piotrus-g - 6/22/14 at 8:56am